本文選題：NO + 催化氧化��； 參考：《杭州電子科技大學(xué)》2016年碩士論文

【摘要】：當(dāng)今中國(guó)環(huán)境污染日益嚴(yán)重,其中的NO_x是引起霧霾的一種很重要的污染物。工業(yè)上NO_x脫除的技術(shù)主要是SCR(Selective Catalytic Reduction,選擇性催化還原法)和SCO(Selective Catalytic Oxidation,選擇性催化氧化法)。由于單獨(dú)的NO在參加SCR反應(yīng)的時(shí)候效率不如NO和NO_2按一定比例參加反應(yīng)時(shí)的高,所以發(fā)展出了快速SCR技術(shù)。不論快速SCR還是SCO,將NO催化氧化為NO_2的技術(shù)均占有重要的地位。而目前,對(duì)NO催化氧化的研究以實(shí)驗(yàn)為主,機(jī)理還不是很清楚。所以,基于NO的催化氧化在脫硝領(lǐng)域的重要作用,本文對(duì)其催化機(jī)理進(jìn)行了詳細(xì)地研究。首先,本文采用量子化學(xué)密度泛函理論對(duì)NO的直接氧化反應(yīng)進(jìn)行了計(jì)算研究,分析了優(yōu)化方法與基組對(duì)計(jì)算所帶來(lái)的影響,并以此作為與催化氧化反應(yīng)對(duì)比的參照。之后,采用UB3LYP//SDD方法優(yōu)化得到負(fù)載在分子篩ZSM-5不同原子附著位點(diǎn)(Si、Al、Ce)上的以Mn、Co為代表的過(guò)渡金屬催化氧化NO相關(guān)反應(yīng)的反應(yīng)物、過(guò)渡態(tài)、中間體及產(chǎn)物,分析得到反應(yīng)進(jìn)程,并計(jì)算獲得了反應(yīng)的活化能。最后,通過(guò)分析總結(jié),對(duì)反應(yīng)機(jī)理進(jìn)行了探究。計(jì)算表明:使用UB3LYP//SDD方法計(jì)算優(yōu)化的情況下,Mn-ZSM5或Co-ZSM5催化劑的存在下NO氧化的活化能在40-80kJ/mol左右,而NO直接氧化的活化能在130kJ/mol以上,所以,Mn-ZSM5和Co-ZSM5具有明顯的催化效果;催化劑的附著中心原子不同,活化能也有差異,其中以Ce和Al為附著位點(diǎn)的ZSM-5催化反應(yīng)時(shí)的活化能在40kJ/mol左右,而以Si為附著位點(diǎn)的ZSM-5催化反應(yīng)的活化能要高于70kJ/mol,可知,摻雜了Ce、Al氧化物的催化劑的催化活性更好;通過(guò)計(jì)算得出Mn-ZSM5與Co-ZSM5的催化活性相差不大,總體上比Mn-ZSM5稍好一些。與前人研究的實(shí)驗(yàn)結(jié)果比較后推斷,溫度、氣體空速和載體等一系列因素都會(huì)對(duì)催化效果產(chǎn)生影響,所以,進(jìn)行比較還需考慮更多因素。本文的量子化學(xué)計(jì)算揭示了Mn-ZSM5及Co-ZSM5對(duì)NO氧化的催化反應(yīng)機(jī)理,為過(guò)渡態(tài)金屬催化氧化NO的進(jìn)一步研究提供了理論參考。同時(shí),指出Ce、Al氧化物的摻雜對(duì)催化反應(yīng)具有促進(jìn)的效果,驗(yàn)證了實(shí)驗(yàn)研究的結(jié)論。最后,Mn-ZSM5與Co-ZSM5催化活性的比較可以為以后對(duì)反應(yīng)引入更多因素的研究提供了參考。
[Abstract]:Nowadays, environmental pollution in China is becoming more and more serious, among which NO_x is a very important pollutant causing haze. Industrial NO_x removal techniques are mainly SCR(Selective Catalytic reduction, selective catalytic reduction, and SCO(Selective Catalytic oxidation, selective catalytic oxidation. Because the efficiency of single no in SCR reaction is not as high as that of no and NO_2 in a certain proportion, rapid SCR technology has been developed. The catalytic oxidation of no to NO_2 plays an important role in both rapid SCR and NO_2. At present, the catalytic oxidation of no is mainly experimental, and the mechanism is not clear. Therefore, based on the important role of no catalytic oxidation in denitrification, the catalytic mechanism of no is studied in detail. Firstly, the direct oxidation reaction of no is studied by using the density functional theory of quantum chemistry, and the influence of the optimization method and the base set on the calculation is analyzed, which is used as a reference to the catalytic oxidation reaction. After that, UB3LYP//SDD method was used to optimize the reactants, transition states, intermediates and products of the transition metal catalyzed oxidation of no on the different atom attachment sites of molecular sieve ZSM-5. The reaction process was analyzed. The activation energy of the reaction was calculated. Finally, through the analysis and summary, the reaction mechanism is explored. The results show that the activation energy of no oxidation is about 40-80kJ/mol in the presence of Mn-ZSM5 or Co-ZSM5 catalyst, but the activation energy of direct no oxidation is above 130kJ/mol, so Mn-ZSM5 and Co-ZSM5 have obvious catalytic effect. The activation energy of the ZSM-5 reaction with ce and Al as the attachment site is about 40kJ/mol, and the activation energy of the ZSM-5 reaction with Si as the attachment site is higher than 70 kJ / mol. The results show that the catalytic activity of Mn-ZSM5 and Co-ZSM5 is not different from that of Mn-ZSM5, and that the catalytic activity of the catalyst doped with Ce-Al oxide is better than that of Mn-ZSM5. Compared with the experimental results of previous studies, it is inferred that a series of factors, such as temperature, gas space velocity and carrier, will affect the catalytic effect, so more factors should be considered for comparison. The quantum chemical calculations in this paper reveal the catalytic mechanism of no oxidation by Mn-ZSM5 and Co-ZSM5, and provide a theoretical reference for the further study of the catalytic oxidation of no by transition metal. At the same time, it is pointed out that the doping of CEO Al oxides can promote the catalytic reaction, and the conclusion of the experimental study is verified. Finally, the comparison of the catalytic activity of Mn-ZSM5 with that of Co-ZSM5 can provide a reference for the further study of introducing more factors into the reaction.
【學(xué)位授予單位】：杭州電子科技大學(xué)
【學(xué)位級(jí)別】：碩士
【學(xué)位授予年份】：2016
【分類號(hào)】：O643.36

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